Mention salient features of human genome.
Salient Features of Human Genome
Some of the salient observations drawn from human genome project are as follows:
$(i)$ The human genome contains $3164.7$ million nucleotide bases.
$(ii)$ The average gene consists of $3000$ bases, but sizes vary greatly, with the largest known human gene being dystrophin at $2.4$ million bases.
$(iii)$ The total number of genes is estimated at $30,000-$ much lower than previous estimates of $80,000$ to $1,40,000$ genes. Almost all ( $99.9$ per cent) nucleotide bases are exactly the same in all people.
$(iv)$ The functions are unknown for over $50$ per cent of discovered genes.
$(v)$ Less than $2$ per cent of the genome codes for proteins.
$(vi)$ Repeated sequences make up very large portion of the human genome.
$(vii)$ Repetitive sequences are stretches of $DNA$ sequences that are repeated many times, sometimes hundred to thousand times. They are thought to have no direct coding functions, but they shed light on chromosome structure, dynamics and evolution.
$(viii)$ Chromosome $1$ has most genes $(2968)$, and the $Y$ has the fewest $(231)$.
$(ix)$ Scientists have identified about $1.4$ million locations where singlebase $DNA$ differences ($SNPs-$ single nucleotide polymorphism, pronounced as ‘snips’) occur in humans. This information promises to revolutionise the processes of finding chromosomal locations for disease associated sequences and tracing human history.
What are the goals of $HGP $?
The total number of nitrogenous bases in human genome is estimated to be about:
Expressed Sequence Tags (ESTs) refers to
Which of following is not salient feature of human genome ?
Definitions/Explanation : $DNA$ polymorphism & Sequence Annotation